Their grief can also be worsened by the stress and guilt of living with the person’s substance abuse prior to their death, which is often felt to be premature and could have been prevented.
In response, academics from the Universities of Bath and Stirling have drawn up a set of guidelines for practitioners to help the bereaved.
They are based upon the findings of a three-year study, which interviewed 106 bereaved adults and held focus groups with health and social care professionals.
The researchers found that some bereaved people reported positive experiences; others identified poorer practice resulting from practitioners not understanding this kind of death and the issues involved.
According to Alcohol Concern, alcohol-related deaths have increased by nearly 20 per cent in the past 10 years. In 2012, there were nearly 6,490 alcohol-related deaths.
The latest ONS figures highlight that 2,955 drug-related deaths were registered in 2013 for England and Wales. According to the National Records of Scotland, there were 526 drug-related deaths registered in Scotland in 2013.
Deaths from substance use can occur in various ways, ranging from a young person who dies after experimenting with drugs to an older person who dies from liver failure after long-term alcohol use.
Both the substance use and the death may be considered taboo, leaving those left behind feeling alienated at a difficult point in their life.
The researchers also highlight how bereaved people can be daunted by the myriad of different individuals and organisations they encounter after the death and propose steps for better cross-agency working.
In other circumstances, such as a homicide, people may be offered assistance from a family liaison officer or from victim support workers.
But there is no such single point of support for people left bereaved through alcohol or drugs - something the researchers suggest could be considered.
The guidelines were developed by a working group of practitioners, including the police, drug and alcohol services, health workers, a funeral director, clergy and a counsellor.
Dr Christine Valentine, who led the research, said: “The unique combination of circumstances surrounding the death of somebody from alcohol or drug use can produce particularly severe bereavements.
“The fact that many of us feel uncomfortable or unsure about how to respond to these bereaved people, how we talk about these deaths and the limited support offered, are all symptomatic of the fact that, so far, this group, though sizeable, remains hidden and neglected by research, policy and practice.
“Our research has found that, while poor responses from services adds to their distress, a kinder and more compassionate approach can make a real difference.
“Our hope is that these guidelines - developed for practitioners by practitioners - will provide a much-needed blueprint for how services can respond to these bereaved people.”